Sen. Bernie SandersBernie SandersOPINION | Shailene Woodley: US should run on renewable energy by 2050 Gore: Progressive ideas 'gaining ground' among Democrats The Hill's 12:30 Report MORE (I-Vt.) said he's not sure if Hillary ClintonHillary Rodham ClintonTrump lawyers asking about presidential pardon powers: report CIA director: 'I don't love' Wikileaks Dem rep: Trump threatened Mueller by trying to set limits for Russia probe MORE would be a good president.

"Don't know," he said when asked by Yahoo News about the former secretary of State, who is considered the front-runner for the Democratic nomination in 2016.

"What is her agenda? I don't know. You don't know. She hasn't said," Sanders said.

Sanders, who is considering his own bid from the White House, also suggested Clinton is no sure thing to win the White House or Democratic nomination.

He said the United States does not anoint people to the presidency.

"She has accomplished a lot of very positive things in her career, but I'm not quite sure that the political process is one in which we anoint people,” Sanders said.

"I don't know that she is running, and I don't know what she will say if she runs," he said. "And I'm not running against Hillary Clinton. I'm telling you is this country has more serious problems today than any time since the great depression — those are the real issues."

Sanders said the biggest obstacle to a run would be his ability to put together the infrastructure.  

“Look, it's easy for me to give a good speech, and I give good speeches,” he said. “It is harder to put together a grassroots organization of hundreds of thousands of millions of people prepared to work hard and take on the enormous amounts of money that will be thrown against us.”

Sanders did not shy away from the label Democratic socialist, saying it would make a "damn good platform" if people understood what it is about. 

Comparing the United States to other industrialized countries, he said even the most conservative politicians abroad see healthcare as a fundamental right. He also decried the extreme wealth of a few in the country. 

He cited a statistic that showed the top 1 percent own 38 percent of the wealth in the United States, but the bottom 60 percent only own 2.3 percent. 

“You know what that is?" he said. "That's called oligarchy."